If sequels are a generally tricky proposition, then comedy follow-ups are especially so, particularly when they’re tied to a specific formula. When faced with the prospect of following up “The Hangover,” Todd Phillips and company sided with the surprise hit’s clever formula, a decision that led to a sluggish sense of déjà vu since the second film essentially told the same joke with little variation. With “The Hangover III,” the franchise rolls the dice by blowing up the formula and putting all of its chips on The Wolfpack, a decision that winds up being the only daring move in this surprisingly safe and sentimental conclusion.

That said, it is a slightly daring move that manages to set the film slightly off-kilter, and it’d be thoroughly alienating if the film weren’t so insistent on acting as a nostalgia trip and delivering exactly what it thinks audiences want more of. Back in 2009, borderline sociopathic man-child Alan (Zack Galifianakis) and eccentric criminal Mr. Chow (Ken Jeong) were well-placed pieces in a deceptively complex puzzle; here, they’re oversized bits wedged into a bizarre, slight film that finds the halfway point between crime drama and dark comedy. It might be more apt to say it stumbles upon it since it sort of stalls in both respects, especially when it stares into the abyss and blinks.

In fact, its darkest gags come early when a jubilant Alan bombs down the freeway with his new pet giraffe, which winds up getting splattered all over the freeway after a low bridge decapitates it. The incident leads to a heated confrontation with his father (Jeffrey Tambor), who dies of a heart attack as an oblivious Alan tunes him out with his headphones. After a morbidly amusing and uncomfortable funeral, Alan’s friends and family stage an intervention and tap Doug (Justin Bartha), Stu (Ed Helms), and Phil (Bradley Cooper) to drive him to a rehab clinic. Their trip is interrupted by Marshall (John Goodman), a criminal mastermind with a bone to pick with Chow, who recently escaped from his Bangkok prison.

After taking Doug as insurance, Marshall charges the Wolfpack with tracking down the fugitive in an effort to recover some stolen gold, but the proceedings quickly degenerate into an Alan and Chow routine. For a series that’s been predicated on the disconnect between its characters’ disparate personalities, there’s shockingly little for Bradley and Helms to do here besides play second fiddle to the outrageous duo. Like other franchises before it, “The Hangover” mistakenly amplifies some of its characters to the point of near-parody, which is especially dangerous in this case considering the already outrageous nature of Chow and Alan. Of course, you could pick worse characters to lean upon so heavily, but the film misses the ensemble, buddy comedy nature that made the first two so oddly endearing.

Sometimes, it doesn’t even feel like a comedy at all, as its set-up leads to an admittedly clever caper film down in Mexico, which allows the film to stretch its legs and introduce audiences to this somewhat bold new “Hangover” entry. After finding Chow in Tijuana, the Pack reluctantly teams up with the criminal to recover the gold to satiate Marshall, and it’s one of the few times the film really clicks since the entire group plays off of each other. There’s a sequence that requires Chow and Stu to break into a mansion while acting like dogs that’s quite funny because Helm’s finicky shtick is a perfect contrast for Jeong’s wildly blasé sense of abandon. The film also moves well at this point, especially since there’s a relative sense of unpredictability and danger once the heist graduates from a comedy of errors to an outright farce, with the fallout even resulting in a death of a somewhat familiar face.

Unfortunately, the film squanders all of that in favor of revisiting Vegas. While “The Hangover III” doesn’t retread the beats of its predecessor, it settles for a parade of call-backs and a general sense of debauched familiarity. Stu’s ex-wife (and now ex-escort) Jade (Heather Graham) cameos along with her on-screen son, who was last seen as a baby whose head was nearly caved in by Alan’s reckless attempt at babysitting. The diversion is worthwhile if only for Alan’s uncomfortably funny and weirdly touching reunion with the boy in a scene that cuts right to the odd, sentimental heart of “The Hangover III,” a film that’s less concerned about reveling in mayhem and hijinks than its predecessors, especially since the guys are actually tasked with being a buzz kill for Chow’s unhinged, semi-apocalyptic party atop Caesar’s Palace, which brings the trilogy’s drug and alcohol fuelled rampaging full circle.

Despite the similarly apocalyptic marketing (“It all ends” in this film, or so we’ve been told), “The Hangover” doesn’t end with a fiery bang that consumes everyone for their past sins (again, this is not an especially dark movie despite the premise) but rather with small, quiet realizations about growing up. This is obviously threaded through Alan’s arc in the film, which still sees him undergo a rehab of sorts through this latest misadventure. Such an approach justifies the heavier focus on this character—this might be Alan’s show rather than the entire Wolfpack’s, but it provides a logical storyline progression that’s perhaps more fulfilling than repeating the expected formula for the second time.

Galifianakis once again brings a presence that’s hard to deny. Overgrown man-child really doesn’t begin to describe Alan, a character so far removed from anything resembling grace and tact that he should be abhorrent. There’s something incredibly impish about him, though, as Galifianakis finds a childlike quality that makes him more than just the franchise mascot. I don’t know that “The Hangover III” qualifies as an intricate character study, but Alan’s arrested development provides a decent enough through-line; if the previous films were centered on the Wolfpack’s attempt to find a lost companion, then this one presents an oddly existential struggle for Alan’s self-discovery. Of course, it’s also a movie that features Ken Jeong shooting and suffocating chickens (for whatever reason, the film’s mean streak mostly extends towards animals), so it’s not exactly Bergman.

Still, the film is often funny; it’s not consistently riotous like the first two films, nor is there an outrageous, signature set-piece, but I found myself chuckling throughout. “The Hangover III” expectedly derives most of its humor from Galifianakis’s routine, which runs the gamut from physical gags to unrelenting awkwardness. It’s the latter that worked most for me—there’s an offbeat smallness about this third film that flies in the face of its insane premise, and many of its funnier moments involve non sequitur asides, chance encounters, and deadpan line readings from Galifianakis (perhaps the most effective thing about the film is how he completely throws himself into the Alan character without acknowledging the absurdity). For every broad, insane moment (like Chow parachuting through the Vegas night crooning “I Believe I Can Fly”), there’s a few more oddly effective ones, such as Alan pestering Phil about his shirt or his gross, awkward run-in with a pawn shop employee (a welcome Melissa McCarthy).

It all adds up to an experience that’s just satisfying enough. Since the series has treaded around some dark edges, it would have been fitting for “The Hangover III” to plunge right into it, and, for a brief moment, it looks to take the leap. Instead, it opts to play it safe with a most straightforward misadventure that feels ill-fitting and appropriate all at once. Even though the film is helmed with tremendous confidence by Phillips, who often infuses the film with epic import and atmosphere (the Wolfpack’s return to Vegas is electrically styled, and the film is generally well-shot), it’s still a little misshapen and offers proof that it’s hard for this franchise to back out of its own formulaic corner. Its characters do their best to claw out, but they aren’t matched with a strong enough premise to truly send this franchise out in memorable fashion.

“The Hangover III” might actually capture the haziness of its title, as it’s a listless, half-remembered little coda for a series that’s never been quite as ballsy as it would have you believe; it follows, then, that its supposed conclusion would resist the opportunity at actual subversion. In fact, it has the most obvious of relapses during a mid-credits sequence that proves that this franchise will always be the sum of its parts—indeed, it’s tough to have “The Hangover” without an actual hangover.